This study investigated reactions in passively loaded, fully extended elbow joints in 13 men. Pain reactions during and after loading were studied, as were endurance time, T(end), and resumption time, Tr. The loading moment on the elbow joint, Mn, varied between 7 and 100% of maximum elbow moment. Discomfort/ pain was estimated with Borg's CR-10 scale. T(end) decreased with increasing load level. The opposite was found for the resumption time: the higher the load, held until T(end), the shorter the Tr. The pain limiting the working capability originated mainly from muscle tissue and not from the joint itself. It is concluded that the relation between load and endurance time for passively loaded, fully extended elbow joints resembles that for muscular loading in more 'normal' postures. Equations for estimation of endurance and resumption times (in minutes) for fully extended joints are proposed: T(end) = 20.6e(-6.04Mn) and Tr = 0.0167e(8.84/(1.46+0.346Mn)), respectively.

In this study effects of low loads in fully flexed postures were investigated. Thirteen men who were unused to the postures participated. Thirteen professional construction workers with long experience of suchlike postures were also studied. Pain reactions during and after loading were observed, as well as endurance time and the recovery process, here by studying the resumption time. Endurance and resumption times differed little from those given by models used for more common postures. Pain from the legs and not from the back limited the working ability in 86% of the endurance tests. Thirdly, the construction workers had significantly longer endurance time and shorter resumption time.

The aim of this study was to investigate fatigue reactions in eye-level work with low loads. It consisted of two parts, each with eight men participating. A handle, placed at eye-level 0.5 m in front of the body, was pushed at three different loading levels, varying between 1 and 20 % of maximum voluntary contraction (MVC). Sustained contractions were performed a) until exhaustion at endurance time Tend during registra-tion of subjective ratings of discomfort/pain and resumption time Tres, and b) for two minutes during registration of mean power frequency, MPF, of the myoelectric signals (EMG) from the biceps brachii (BB), triceps brachii (TB), trapezius (TZ) and deltoideus (DD) muscles and subjective ratings of discomfort/pain. These parameters were also studied during the following recovery period.The higher the load, the shorter were the Tend and the following recovery period. Also, the Tres decreased with increasing load. The MPF increased in some cases and de-creased in others during the sustained contractions. The levels of decrease/increase in MPF differed for the different loading levels and the different muscles. The largest fa-tigue indications in MPF were in BB while the discomfort/pain originated from TB. TZ showed the smallest fatigue reactions.The results indicate that caution should be taken when developing and using models for estimating physical strain and fatigue based on EMG indications in low loading situations.

Work-related personal injuries, WRPI, lead to human suffering and costs for the community, companies and individuals. Action to reduce the risks must be taken in companies and therefore it is important that companies have adequate knowledge and methods of systematic risk management. However, many companies and organisations lack relevant knowledge about WRPI risks and their consequences. This paper presents two new methods, the Method for Analysing Work related Risks, Improving work environment and estimating total Cost (MAWRIC) and the method for Statistically-based Cost Analysis (SCA). These can be used for risk assessment, for proposing risk-reducing measures and for estimating economic consequences of risks and measures. An example from the construction industry shows that the costs associated with personal injuries may represent 2 % of company turnover and be at the same level as the company's total profit. Only when decision-makers realise the economic consequences of WRPI risks, both for individuals and for their company, does a real interest and incentive for risk reduction arise. It is concluded that the two methods presented can be used as tools to bring risk-associated questions up to management level and to lower WRPI risks and the costs associated with such risks.